NC Bench
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Run: 2026-02-20-01KHYBB91P9M63K4XSQ0P33NA5
Run Details
Model:
Grok 4.1 Fast
Test:
N-Length Sentences
Scenario:
Write sentences with 20 words each
Duration:
5.2s
Cost:
$0.000362
Provider:
xAI
Evaluation summary
Score
Evaluator
Details Link
19.23%
Matches word count
(details)
Model input
User/Human
Please write the opening scene of a murder mystery where each sentence has exactly 20 words. Please make sure that each sentence has the same length. Only return the opening itself.
Model response
Messages
Meta
AI
Thick fog enveloped the ancient cobblestone streets as Inspector Hale slowly approached the looming Victorian mansion at midnight. A trembling butler swung open the massive oak door, his pale face illuminated by the flickering gaslight outside. "Inspector, thank God you've come; Sir Reginald lies dead in the library, blood pooling on Persian rugs." Hale nodded grimly and stepped inside, his boots echoing through the shadowed marble-floored grand foyer entrance. Crystal chandeliers cast eerie shadows as he followed the butler down the dimly lit corridor to the crime scene. The library door creaked open, revealing the aristocrat slumped over his mahogany desk, lifeless eyes staring blankly ahead. A single gunshot wound marred his temple, and the air hung heavy with the sharp scent of cordite smoke. Bookshelves towered around the body, their volumes undisturbed except for one fallen volume on the bloodstained floorboards. Hale scanned the room quickly, noting the French windows ajar and rain pattering on the terrace beyond them. Five suspects gathered nervously in the adjoining drawing room, their faces masks of feigned shock and hidden guilt.
created_at
"2026-02-20T20:20:04.802Z"
2/20/2026, 8:20:04 PM
model
"x-ai/grok-4.1-fast"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
362
moderation_latency
(null)
generation_time
5107
tokens_prompt
46
tokens_completion
351
native_tokens_prompt
191
native_tokens_completion
705
native_tokens_completion_images
0
native_tokens_reasoning
475
native_tokens_cached
190
num_media_prompt
(null)
num_input_audio_prompt
(null)
num_media_completion
0
num_search_results
(null)
origin
"https://ncbench.com/"
is_byok
false
finish_reason
"stop"
native_finish_reason
"completed"
usage
0.0003622
router
(null)
provider_responses
0
endpoint_id
"9821aa0e-dce3-4c27-9716-161359123d0b"
id
"3c6a275a-62f9-2e9c-5b02-1bbc7ba03209"
is_byok
false
latency
95
model_permaslug
"x-ai/grok-4.1-fast"
provider_name
"xAI"
status
200
api_type
"completions"
id
"gen-1771618804-rCfENZZCHvwxk2sd0taL"
upstream_id
"3c6a275a-62f9-2e9c-5b02-1bbc7ba03209"
total_cost
0.0003622
cache_discount
0.0000285
upstream_inference_cost
0
provider_name
"xAI"
Evaluation details
Result
Evaluator
Details
Meta Data
19.23%
Matches word count
n/a
neededClean
false
sentences
10
wordCounts
0
18
1
18
2
17
3
17
4
19
5
18
6
19
7
17
8
18
9
18